ABSTRACT Project background: Obstructive sleep apnea (OSA) is a prevalent condition that is most frequently treated with continuous positive airway pressure (CPAP) therapy. Non-adherence to such therapy, however, afflicts a high proportion of adults with sleep apnea (46-83%). Moreover, such non-adherence to CPAP is associated with increased risk for fatal and non-fatal cardiovascular events. There remains a paucity of reliable and cost- effective interventions that could promote CPAP adherence. Promoting adherence to therapy through peer- driven intervention is cheap and has met with modest success in other chronic conditions such as HIV, heart failure and diabetes mellitus. Whether such a peer-driven ("buddy") system can improve adherence to CPAP therapy is unknown. Project Objectives: Our overall aim is to assess the feasibility and acceptability of a CPAP adherence program driven by trained "peer-buddies" with sleep apnea. Specific Objective #1: To evaluate patient ratings of the acceptability of the peer buddy system (PBS) in veterans receiving CPAP therapy for OSA. Specific Objective #2: To obtain preliminary data on the effectiveness of PBS on sleep-specific HR-QOL (Functional outcomes in sleep questionnaire [FOSQ]) in veterans receiving CPAP therapy for OSA. Specific Objective #3: To obtain preliminary data on the effect of PBS on CPAP adherence, vigilance, patient activation, and self-efficacy in veterans receiving CPAP therapy for OSA. Project Methods: In order to address these aims, we will recruit recently diagnosed patients with OSA who have not been initiated on CPAP therapy and randomly assign them to the peer-buddy system to promote adherence to CPAP therapy (intervention group) or be assigned to usual care (control group). In the PBS- intervention group, trained peers with sleep apnea will be paired with the newly diagnosed patients over a 3- month period. During this time the trained peers will share experiences on coping strategies with CPAP device and equipment (promote self efficacy), share their positive experiences (motivational effects and outcome expectancies), share their knowledge of perceived vulnerabilities due to untreated sleep apnea (promote risk perception), share methods for improving efficacy of CPAP equipment and interface (patient education) and prepare their subjects for upcoming physician or respiratory therapist appointments (patient activation). The interaction will occur during supervised "in-person" sessions and during telephonic conversations over the 3- month period. Subjects from both groups will be reassessed at the end of 3 months in order to determine objective measures of CPAP adherence, sleep-specific HRQOL (Functional outcomes of sleep questionnaire [FOSQ]), vigilance (psychomotor vigilance testing), measures of self-efficacy (outcome expectancy, treatment self-efficacy, and risk perception [SEMSA questionnaire]) and patient activation (Patient Activation Measure [PAM]).